1. Field of the Invention
The invention relates in general to a memory device, and more particularly to a memory device used as an augmented memory of the portable electronic device.
2. Description of the Related Art
Portable electronic products, such as mobile phones, MP3 players, personal digital assistances (PDA) and digital cameras for instance, have gained a great popular interest nowadays. As the portable devices are featured by lightweight, slimness, compactness and versatile functions, the need for the storage and sharing of multi-media information is growing rapidly. It is a great challenge to provide an information storage medium with smaller volume, lower power consumption and a larger storage capacity.
Most of the current portable electronic devices adopt a flash memory card to enlarge the capacity of memory for storing or sharing multi-media information. The flash memory card has a variety of types, and memory cards with various specifications are applicable to different electronic devices. Compact flash (CF) card is the earliest and most popular product in flash memory cards, so almost every digital camera and PDA has a CF augmentation port. Despite the CF card is slow in reading and writing speed, it is the cheapest one of memory cards in the market. Smart media (SM) card is smaller in volume size and faster in reading and writing speed than the CF card. SM card is suited for use in parts of the portable electronic products for Japanese specifications. The manufacturers present a multi media card (MMC) whose size is equivalent to but slightly thicker than the SM card. New style MMC card overcomes the shortcoming of the slow speed of the CF card in reading and writing, but is applicable to fewer electronic devices and has higher price than the CF card. As the urge of the protection of digital copyright is attracting more attention, the secure digital (SD) card, which is similar to appearance of the MMC card and equipped with encryption and high-speed transmission functions, is provided. Moreover, the hardware that supports the SD card is also compatible with the MMC card. Apart from the above mentioned memory card, there are a variety of memory cards for reduced-size, such as Mini SD card and reduced-size multi-media card (RS-MMC). Beside, the memory stick (MS) presented by the Sony Corporation is exclusively applicable to Sony portable electronic devices including PDA, video camera, digital camera, and so forth.
No matter which memory card disclosed above is used, when data have to be transmitted between two different electronic devices, a card reading machine will be needed if one of the electronic device lacks a suitable read-write socket. A card-reading machine is required to transmit the photos stored in the memory card of the digital camera to the computer, since most computers in the commercial market aren't equipped with a socket compactable for the flash memory card. Therefore, it is inconvenient for the user to transmit the data stored in the flash memory card to the electronic devices incapable of reading flash memory cards (including CF card, SM card, MMC card, SD card, and MS card) directly.